This invention relates to ring laser gyroscope in general and more particularly to a novel anode that permits operation at substantially lower currents, which in turn allows operation of the ring laser gyroscope with a considerable reduction in the heat dissipation.
As is inherent in its name, the ring laser gyroscope uses a laser beam which travels in a closed path. Regardless of whether the closed path is triangular, rectangular, pentagonal, etc., the closed path is commonly referred to as a ring. Such a ring laser gyroscope is used to detect rotation about the axis of the path around which the laser beam travels. Typical ring laser gyroscopes are disclosed in U.S. Pat. Nos. 3,373,650 and 3,467,472. According to the ring laser gyroscopes described in these patents, there is included a triangular block which forms a triangular-shaped ring laser cavity defined by mirrors at the three corners.
As is understood by those skilled in the art, and as will be further discussed with respect to prior art FIG. 1 hereinafter, a ring laser gyroscope is typically made of a glass ceramic material which forms an optical cavity. The selected lasing gas is used to fill this optical cavity. Mirrors are positioned around the optical cavity at appropriate locations such that the laser beam is reflected in a triangular shape through the optical cavity. A glow discharge is created in the gas filled optical cavity by means of anodes and cathodes which are in communication with the gas filled optical cavity. In the prior art ring laser gyroscopes, the paths by which the anodes and cathodes communicated with the gas filled optical cavity were capillaries leading to that portion of the gyroscope at which anodes and cathodes were mounted. Thus, because of the very high dielectric index usually associated with the ceramic material from which the cavity was made, stray capacitance existed between the anodes and the glow discharge in the capillaries. Furthermore, stray capacitance also existed between the anodes and surrounding areas and portions of the gyroscope and mounting structures. This stray capacitance between the anode and other structures is believed to be the chief reason for current instabilities in the glow discharge. Therefore, it is an object of this invention to provide a ring laser gyroscope which reduces the stray capacitance between the anodes and other structures as well as between the anode and the capillary path containing the glow discharge.
In addition, presently available ring laser gyroscopes necessarily must use a low gas pressure in the gas filled cavity which results in considerable sputtering of the cathode. Even a small increase of the gas pressure in the ring laser gyroscope would result in a substantial reduction in the sputtering of the cathode. Therefore, it is another object of this invention to provide a ring laser gyroscope which operates at a higher gas pressure without simultaneously having a plasma oscillation condition.
It is also understood by those skilled in the art that if a lower anode current can be used without a drop out of the glow discharge, there will be a considerable reduction of power consumption and consequently heat dissipation in the gyroscope due to the lower currents. Therefore, it is still another object of this invention to provide a ring laser gyroscope having reduced power consumption and heat dissipation.
Since temperature variations or gradients in the plane of the triangular structure of the ring laser gyroscope, causes gas currents to flow, it is not unusual that a false input rate may be indicated because of such gas currents. Thus, since increasing the fill pressure of the gas cavity reduces the sensitivity to temperature variation, it will be appreciated that a reduction in power consumption and consequently in heat dissipation will increase the stability of the ring laser gyroscope itself. Thus, it is another object of this invention to increase the stability of a ring laser gyroscope.